Manifold for internal combustion engines



Sept. 12, 1933. F. E. ASELTINE MANIFOLD FOR INTERNAL COMBUSTION ENGINES 3 Sheets-sheet- 1 Original Filed Sept. 5,

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Sept. 12, 1933. F. E. ASELTINE 1,926,019

IANIFOLD FOR INTERNAL COMBUSTION ENGINES Original Filed Sept. 5, 1 925 5 Sheets-Sheet 5 Patented Sept. 12, 1933 Original application September 5 1925,. Serial No. 54,592, new Patent No. 1,727,265. Divided and UNHTED' STATES PATENT OFFICE this application June 29, 1929. Serial No.

21 Claims.

This invention relates to charge forming devices for internal combustion engines and more particularly to the intake manifold for a multicylinder engine of thistype.

The present application constitutes a division of my prior application Serial Number 54,592, filed September 5, 1925; now Patent No. 1,727,265.

It is the principal object of the present inven tion to provide an intake manifold for an internal combustion engine of the character described which is provided with automatically operated means for variably restricting the outlet branches of said manifold adjacent the outlet ends of said branches, whereby the fuel charge supplied to the ports is delivered thereto at relatively high velocity, thereby preventing the depositing cf liquid fuel particles on the walls of the outlet branches.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. l is a plan View of a charge forming device for a six-cylinder internal combustion engine, built according to this invention.-

Fig. 2 is a section on line 2-2 of Fig. l and shows the relation of one branch of the intake pipe to the engine intake valve of an L-head engine.

3 is a side elevation of the device shown in Fig. l, and shows the manually actuated arm for changing the spring tension on the spring closed main air inlet valve.

Fig. 4 is a vertical section on the broken line ll of Fig. l and shows in particular the liquid fuel ducts leading from the float bowl to the two at uting canals for the primary carburetors.

fig. 5 is a vertical section on the broken line 5-5--5 of Fig. l. v

Fig. 6 is a section through one of the primary carburetors and is taken on the line 6-6 of Figs. 1 and 8.

Fig. I is a plan view of the central part of the device with the distributing block containing the primary carburetors removed, and shows in dot and dash lines the position of the distributing canals contained in said distributing block.

Fig. 8 is an enlarged plan view of the distributing block containing the distributing canals for the three primary carburetors shown in dotted lines therein.

Fig. 9 is a bottom view of the distributing, block.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Numeral 1 0 designates in its entirety the air manifold provided with the three branches 11, 12 and 13, each of which branches connects to an engine intake port, whichserves two adjacent cylinders. Since it is well known in both four and six cylinder engines to provide only one engine intake port to serve two adjacent cylinders, such engine construction is not shown in detail in the drawings. Fig. 2 shows only one engine intake valve 15 of the pair of similar intake valves served by the branched intake passage 14 and intake port 16 in the cylinder block casting. The air manifold casting 10 has amain air inlet opening 17 which is covered by the air inlet fitting 18 having the main air inlet 19 and the intake valve 20. Located directly under the in let valve 20 is the fuel float chamber which is provided with the annular float 3'1 and float-operated fuel inlet valve 32 for maintaining constant fuel level in chamber 30'. Liquid fuel from a suitable supply tank is led to the valve 32 through the pipe connection 33, hollow screw 34 and duct 35, all as clearly shown in Fig. 5.- This duct 35 and its related parts are preferably carried in a casting 36 which is separate from the manifold casting 10, but which is held in rigid relation therewith by the internesting circular flanges 37 and 38, and the two clamping bolts 40 whichextend through suitable ears onthe castings l0 and 36. These clamping bolts 40 also extend through suitable ears on the air inlet fitting 18 and the float bowl 30, and thus clamp all these parts rigidly together, as clearly shown in Fig. 3.

The main air inlet valve 20 has a valve stem extending down through the guide 51 in cas ing 36 and is provided at its lower end with a dashpot piston 52 which cooperates with the dashpot cylinder 53 located within the fuel bowl 30 and surrounded by the annular float 31 therein. The piston 52 has one or more holes 54 therein (two being shown in Fig. 4) and a loose disk check valve 55 for closing the holes 54 upon downward movement of the piston, as will-be clear from Fig. 4. The dashpotcylinder 53 remains filled with liquid fuel at all times, the fuel entering through suitable holes 56 above the piston 52 but below the fuel level 57- infloat bowl 3-0. The wall of the dash pot cylinder 53 is provided with a by-passduct- 58 of about fl -inch diameter, which freely by-passes liquid around. piston 52 after the valve 20 has moved down a predetermined amount to uncover the by-pass port 59 (see Fig. 5). The air valve 20 is urged to its seat by the coil spring 60 whose upper end engages the spring seat disc 61 held against a shoulder on the valve stem 50, and whose lower end engages the vertically-adjustable spring cup 62 which slides within guide cylinder 63 in casting 36. The cup 62 is adjusted up or down by means of a yoke 64 rigidly secured to a transverse shaft 65 having suitable bearings in the casting 36. The two arms of the yoke 64 have slotted extremities 66 engaging diametrically-opposite pins 6'7 on the cup 62. These pins 67 project through and ride in the slots 68 in the walls of the guide cylinder 63 (see Fig. 5). The transverse shaft 65 is actuated by lever arm 69 secured to the projecting end of shaft 65. The tension of spring 60 may be adjusted at will by the operator by suitable manually actuated linkage attached to lever 69 and extending to the drivers seat. The minimum or normal tension on spring 60 is adjusted by the screw '70 which limits the downward movement of cup 62, as will be clear from viewing Fig. 3. The air valve 20 is opened according to the depression in the air manifold 10, its opening move ment being damped by the leakage of fuel past -the dashpot piston 52, the check valve 55 being closed. During its initial opening movement the damping effect is at a maximum, but as the valve 20 opens more and more, the damping effect of the dashpot progressively reduces due to the leakage through by-pass port 59 becoming greater The air valve 20 is permitted to close quite rapid- 1y by the opening of check valve 55 in piston 52 during the upward motion of said piston.

It will be noted that a thin plate '75 is provided to insure that equal parts of the air entering the air inlet horn 19 will flow through the three outlet branches of the manifold. This plate is secured between the air inlet horn and the top of the manifold immediately above the middle outlet branch of saidmanifold permitting a flow past the air controlling valve directly into this manifold branch. The purpose of this plate should be obvious. The resistance to flow through the end branches of the manifold is greater than that through the middle branch because of the greater distance through which the air has to flow, and if air were permitted to flow directly into said middle branch the volumeof air flowing to the engine through said middle branch would be greater than that flowing through the end branches. The

plate 75 operates as a bafiie around which the air flowing through the middle outlet branch of the manifold must pass, making the resistance to flow through, and the volume of charge supplied by, the various branches equal.

The primary carburetors for supplying an overrich fuel mixture to each of thebranches 11, 12

and 13 of the air manifold will now-be described. The casting 36-has an upstanding portion extending upwardly alongside thecentral-branch 12 of the air manifold 10. This portion 80 contains the two vertical fuel ducts 81 and 82, which branch in parallel relation from the fuel duct 83. Duct 83 is extended to a point below thefuel level 57 by the long metering plug 84 which has the fuel-metering orifice 85 therein. The portion 80 terminates at the top in a flat table-86 havingtwo screw-ears 8'7 thereon (see Fig. 7). The distributing block, designated as a whole by numeral 90, has a corresponding flat surface 91 (see Fig; 9), which is rigidly secured upon the table 86 by the two screws 92 which are threaded into the ears 87. The fiat surface 91 of the distributing block is provided with two separate fuel-distributing canals 93 and 94 which register with the vertical fuel ducts 81 and 82, respectively, as shown by the dot and dash lines in Fig. '7. The distributing block 90 contains three parallel bores 95, 96 and 97, of the same diameter, each of which bores extends above and across the fuel-distributing canals 93 and 94 adjacent the open end of each of said bores (see Figs. 8 and 6). The fuel canal 93 admits fuel to each of the bores 95, 96 and 97 through a high-speed fuel jet 98, and the canal 94 admits fuel to each of said bores by a low-speed fuel jet 99, thus forming three individually-metering primary carburetors 100, 101, and 102. Primary air enters each of these carburetors through an air-metering bushing 105 which projects into the bores 95, 96 and 97 past both fuel jets 98 and 99 (see Fig. 6). The fuel jets 98 and 99, therefore, deliver fuel to the annular space 106 between the bushing 105 and the walls of the corresponding bore, and hence the entering air does not impinge directly upon the fuel jets. Any variation in the flow of fuel through these jets due to turbulency in the entering air stream is thus avoided and hence more accurate and uniform metering of the liquid fuel is obtained. The vertical fuel duct 81 contains a gravity metering valve 88 whose tapered end cooperates with the valve seat 89. During idling or low engine speeds this valve 88 rests upon its seat 89 and hence fuel is supplied to the primary carburetors 100, 101, and 102 only through canal 94 and the low speed jets 99. As the engine speed is increased by opening the manually-actuated throttles, the suction on the primary carburetors is increased sufficiently to cause the liquid fuel to lift valve 88 from its seat and thus permit fuel to also flow through the high-speed jets 98 in the primary carbureters. The valve 88 is lifted more and more, according to the increase in enginev speed and hence acts as a variable restriction or metering orifice for the high-speed jets 98. The weight of the valve 88 is made such that it remains upon its seat at engine speeds below about 400 R. P. M. or a car speed of about 10 miles per hour. At this speed valve 88 begins to pass a small amount of fuel to the high-speed jets 98 and. as'the speed increases from this point on the jets 98 supply a progressively increasing amount of fuel to the primary carburetors. Of

. course, the relative sizes of the various jets and orifices and the weight of valve 88 must be so chosen that the primary carburetors function properly, as described above. The following weights and sizes have been found to give good results with a six cylinder 36 H. P. automobile engine: weight of Valve 88, 3 /2 grams; diameter of valve seat 89, of an inch; size of each of jets 98, No. 60 drill; size of each of jets 99, No. '73 drill; size of fuel orifice 85 supplying total fuel for all three primary carburetors, No. 53 drill; size of each of primary air orifices 105, No. 35 drill.

The overrich air-and-fuel mixture from the primary carburetors 100, 101 and 102 is led directly into the throat portion of a relatively large venturi 110 in each of the branches 11, 12 and 13 of the air manifold. The bore of the distributor block 90 leads directly to the hole 111 in the central branch 12, the distributor block being rigidly anchored to branch 12 by the screw 112. The bore 96 leads through a small pipe 113, of about the same diameter as said bore, to the pipe fitting 114, which is rigidly secured to the branch 13 by the screw 115, so that the duct 113 registers with the hole 111 which leads down into the throat of the venturi 110 in the branch 13. Each of the venturi 110 is held tightly up against a shoulder 116 in each branch by a tapered'set screw 117 which rides against a cam surface 118 on the venturi (see Fig. 2). Preferably the floor 120 or" the air manifold 13 is raised to lie approximately on a level with the bottom 121 of the throat of venturi 110. This prevents the puddling of liquid fuel on the floor 120 ahead of the venturi 110 at low throttle openings and enables the entering air stream to more easily sweep all liquid fuel which may be deposited upon the floor of the venturi into the branch 13 and thence into the engine cylinder. The small amount of liquid fuel which may accumulate inthe small crescent-shaped depression 122 at low throttle positions will have no deleterious effect. However, this depression 122 may be avoided simply by filling with metal, that is, by designing the venturi 110 so that its bottom portion completely fills the depression 122 and lies flush with the driver.

floor 120.

A throttle valve 125 is located in each of the branches 11, 12 and 13 immediately behind the venturi 110 to control the fuel charge entering each engine intake port 16. Each throttle 125 is mounted upon a separate rotatable shaft 126 having bearings in suitable bosses 127 integral with the respective branches. The three shafts 126 are all interconnected by the two shafts 123 which are connected to the projecting ends of the shafts 126 by means of the universal joints 130. The universal joints 130 each comprise a twoarmed spider 131 rigidly secured to one end of shaft 128, and a similar two-armed spider 132 adjustably secured to one end of a throttle shaft 126 by the clamping screw 133. The two spiders 131 and 132 are ri idly riveted to a thin annular ring 135 of flexible metal by means of the rivets 134. t will be clear that these universal joints 130 not only render the exact alignment of throttle shafts 126 unnecessary, but also that they will permit relative longitudinal movement between the two coupled shafts and hence will eliminate any possible binding of the accurately fitted throttle valves 125, due to unequal expansion of the manifold 10 and the shafts 128 and 126. Each throttle 125 may be rotatably adjusted relative to the universal coupling 130 by loosening the screw 133 and turning shaft 125 within the boss of spider 132. By this means the throttles 125 may be accurately adjusted after assembly, so they will all close exactly together. One of the universal coupling members 132, preferably one attached to the central throttle shaft 126, is provided with 21. depending lever arm 136 by which means all the throttles 125 are concurrently manually actuated. Suitable mechanical linkage (not shown) connects the lever arm 36 to an ordinary hand throttle lever or foot accelerator, located in convenient reach of the The lever arm 135 is also provided with the usual idle-position-adjusting screw 13'? which engages the stop lug 138. These parts are shown only in plan in Fig. 1., but it is thought the construction will be clear when taken with the above description.

In order to increase the velocity of the fuel mixture as it enters each of the engine intake ports 16, an automatic passage-restricting means is provided in each of the branches 11, 12 and 13 (see Fig. 2). This means comprises a thinwalled inner tube 140, of slightly less diameter than the inside diameter of the branch 13, which is held rigidly in place against the top wall of the branch by the screw 141 and two or more lugs 142 which are preferably tongues, cut out of the metal of tube 140 and turned down at suitable angles to form legs for spacing the tube 140 from the bottom of branch 13. Within the tube 140 are mounted two flapper valves 143 which pivot upon the centrally-mounted shaft 144. The valves 143 are urged to closed position by the small coil tension springs 145 which are suitably fastened at one end to the valves 143 and at the other end to the eyes 146 in the spring support 147 which, preferably, is also pivoted upon the shaft 144 in central slots in the valves 143. The springs 145 are made sufficiently strong to hold valves 143 closed when the throttle 125 is in its nearly closed positions and thus compel all the entering charge to pass through the restricted crescent-shaped passage 148 between the tube 140 and the walls of branch 13. The velocity of the entering charge is thereby greatly increased and passes up to the engine intake valve at high speed, thus carrying all the unvaporized fuel particles therein into the engine cylinder and preventing any deposition of accumulation of liquid fuel upon the floor or walls of the engine intake passage 14. Preferably the tube 140 extends a short distance within the passage 14, as clearly shown in Fig. 2, in order to carry the restriction in the intake passage beyond the engine ports 16, so that the entering charge will be given less chance to slow down materially before entering the valve 15. As the throttle valve 125 is opened to admit a greater charge to the engine, the springs 145 will yield according to the entering blast upon the flapper valves 143 and permit the valves 143 to open to a position to pass this greater charge at a surficiently high velocity to prevent deposition of liquid fuel in the passage 14. When the entering charge has reached a maximum value, that is, when the throttle 125 is full open and the engine is running at high speed, the two valves 143 large charges no restriction by the valves 143 is needed to prevent deposition of liquid fuel in intake passage 14 and hence the resisting force of springs 145 on valves 143 when in full-open position is made only large enough to properly initiate the closing movement of the valves upon the next reduction in the amount of incoming charge. Thus any tendency of the valves 143 to reduce the volumetric efficiency of the engine at full throttle is practically overcome.

A depression-equalizer tube 150 interconnects all the branches ll, 12 and 13 at a point between the throttle 125 and the engine cylinders. At low-opening throttle positions this tube 15 causes a substantially-constant equal depression on the engine side of the throttles in all the branches 11, 12 and 13, and hence causes each of the six engine cylinders to draw in equal charges. The method of functioning of this equalizer tube is described in greater detail in to enter through low-speed jets 99, forming a' rich mixture to be delivered to each venturi 110 through holes 111. At such times only a very small amount of air enters the manifold 10 through the spring-closed air valve since the depression in air manifold 10 is small, and hence the rich mixture entering the branches through the holes 111 is not over-diluted with air from the main air inlet 19. Now, when it is desired to increase the engine speed, the throttles 125 are opened wider, which, of course, increases the depression in manifold 10. This increased depression is transmitted back to the primary carburetors and causes them to deliver a still richer mixture to the branches through the holes 111 due to the functioning of the second fuel jets 98. This increased depression in manifold 10 also opens the air valve 20 further and admits a greater amount of air to properly dilute the rich fuel mixture through holes 111, thus maintaining the proper ratio of air and fuel going to the engine. The dash pot 52, 53 prevents possible fluttering of the air valve 20 due to pulsations of the engine suction, especially at low engine speeds,

and also damps the opening of air valve 20 in order to cause the increased depression in manifold 10 to act first on the primary carburetors upon the opening movement of the throttles 125.

The dashpot by-pass 58 progressively reduces this damping eifect upon air valve 20 as the throttles 125 reach their more fully-open position with the engine running at high speed, since under these conditions this damping effect is not so much desired. If at any time it is desired to increase the richness of the mixture, for instance when starting the engine, the operator actuates the lever 69 to increase the compression on spring 60. This, of course, permits less air to enter valve 20 than otherwise would under the then conditions and hence permits the primary carburetors to deliver a richer mixture to the engine cylinders. Preferably the operating linkage for lever 69 is arranged to hold it in any position to which the operator may move it, thus permitting the operator to run the engine for any desired period of time on an enriched mixture. It is pointed out that the lever 69 does not act simply as an ordinary choking arrangement since the valve 20 is still permitted to open according to the depression in manifold 10 and thus func-' bellows 1631s sealed to the bottom of chamber A passage 162 in plug 161 forms communica-' 160 and a coil spring 164 therein serves to urge the wall 165 of bellows 163 upwardly into contact with the plug 161, as shown in Fig. 4. The interior of bellows 163 communicates through passage 166 in the pipe connecting plug 167 with a small duct 168 which leads to the engine intake above the throttles 125. This duct 168 preferably branches from the equalizing tube 150 at some convenient point, and thereby maintains a uniform depression in bellows 163 equal to the average depression in all three of the branches ll, 12 and 13 above the throttles. t all lowopening throttle positions, this depression in bellows 163 collapses said bellows until the wall 165 thereof engages the adjustable stop pin 170 which is threaded into the plug 167 and provided with a lock nut 171 for holding the pin 170 in adjusted position. When bellows 163 is collapsed, fuel is drawn through passage 162 to fill the chamber 160 around about said bellows. Now when the throttles 125 are suddenly opened by the driver to accelerate the car the depression in equalizer tube 150 and hence in bellows 163 is suddenly reduced, thereby permitting spring 164 to expand the bellows, thus pumping fuel from chamber 160 into the dashpot 53. Obviously this action opposes the opening movement of the main air valve 20 momentarily and thus causes a richer mixture to be delivered to the engine to give a more powerful accelerating charge. The exact amount of fuel pumped into the dashpot 53 to give the proper accelerating effect may be accurately adjusted by the vertical adjustment of the stop pin 170, as clearly illustrated in Fig. 4. The strength of bellows spring 164 is preferably so chosen that the bellows 163 will not be collapsed by the depression therein when the throttles 125 are in their more open positions, for instance, at one quarter open and above. Therefore further sudden opening of the throttles from such positions will not be accompanied by an increased resistance to the opening of air valve 20 due to a pumping action of bellows 163. Such cutting out of the accelerating device at the larger throttle openings is usually desired since, ordinarily, at the higher engine speeds there is no temporary starving of the engine under a sudden increase in the throttle openmg.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports, a manually operable throttle in each branch, and automatically operated means in each branch, for controlling the flow therethrough whereby surging of the fuel charge within the manifold is prevented as the outlet branches are successively rendered effective.

2. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports, a manually operable throttle in each branch, and a suction operated means in each branch adjacent the intake port for controlling the flow therethrough whereby. surging of the fuel charge 3. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports, a manually operable throttle in each branch, a suction operated valve in each branch adjacent the intake port which is adapted to be opened when the fuel charge is drawn into a cylinder associated With said port, and means for autmatically closingsaid valve at all times when the fuel charge is not being drawn into said port, irrespective of the position of the manually erable throttle.

i. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports and an inlet admitting air to said manifold, conduits for supplying a primary mixture of air and fuel to said manifold branches, and means in said branches adjacent their outlet ends for increasing the velocity of flow therethrough.

5. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports and an inlet admitting air to said manifold, conduits for supplying a primary mixture of air and fuel to said manifold branches, and means for automatically and variably restricting said branches relatively near their outlet ends for increasing the velocity at which the mixture is delivered to the intake ports.

'6. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with such intake ports and inlet admitting air to said manifold, conduits for supplying aprimary mixture of air and fuel to said manifold branches, and suction operated valves in said branches between the conduits and the outlet ends for increasing the velocity at which the mixture is delivered to the intake ports.

7. An intake manifold for multicylinder inte l combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports, conduits for supplying a primary mixture of air and fuel to said manifold branches, manually operable valves in said branches for regulating the fiow therethrough and suction operated valves in said branches for automatically controlling the flow therethrough.

8. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports, comprising a plurality of outlet branches associated with said intake ports, conduits for supplying a primary mixture of air and fuel to manifold branches, manually operable valves in the branches adjacent said conduits, and suction operated valves in said branches adjacent their outlet ends.

9. In combination with the intake pipe of an internal combustion engine having an intake port, a blast opened passage-restricting means located Within said intake pipe adjacent said intake port, said means comprising: an inner duct partially filling the sectional area of said intake pipe, and a spring closed valve within said duct which is tensioned to remain closed at slow engine speed and to open according to the blast of the entering charge at higher engine speeds.

10. In combination with the intake pipe of an internal combustion engine having an intake port, a blast opened passage-restricting means located within said intake pipeadjacent said intake port, said means comprising: an inner duct eccentrically mounted within said intake pipe and filling the greater part of the sectional area thereof, and a spring closed valve tensioned to close said inner duct at lower engine speed and to open according to the blast of the entering charge at the higher engine speeds.

11. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a plurality of suction operated flap valves and means for automatically closing said valves in any one of said manifold branches Whenever an engine intake port associated with that particular manifold branch is closed.

12. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated With said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a shaft extending transversely across the manifold outlet branch, a plurality of suction operated valves pivotally mounted on said shaft and extending toward the wall of said outlet branch, and means for moving said valves toward closed position on reduction of engine suction, I

13. An intake manifold for a multicylinder in- 110 ternal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated With'said intake ports, automatically operated means in each branch for controlling the fiow of fuel mixture therethrough, said means comprising a shaft extending transversely across the manifold outlet branch, a plurality of suction operated valves pivotally mounted on said shaft and extending toward the wall of said outlet branch, ears projecting from said 0 shaft and springs for returning said valves to normal position, said springs being connected to said ears and said valves.

14. An intake manifold for a multicylinder internal combustion engine having a plurality of 5 intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a sleeve supported in the end of the outlet branch and supporting means for restricting said branch, said sleeve being spaced from the wall of said branch to permit fuel collecting on the wall anterior to the passage restricting means to flow to the intake port-1 15. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a sleeve adapted to be inserted in the end of the outlet branch, a suction operated valve supported by said sleeve and adapted to restrict the flow therethrough, and 1 means for moving the valve toward its closed position on reduction of engine suction.

16. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet I150 branches associated with said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a sleeve adapted to be inserted in the end of the outlet branch, a suction operated valve supported by said sleeve and adapted to restrict the flow therethrough, a manually operable valve' in said outlet branch and means for moving the suction operated valve toward closed position on closing movements of the manually operated valve.

I 17. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for controlling the flow of'fuel mixture therethrough, said means comprising a removable sleeve adapted to be inserted in the end of the outlet branch, automatically operable passage restricting means carried by said sleeve, and means for retaining the sleeve in adjusted position in the manifold branch. 7

18. An intake manifold for a multicylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for controlling the flow of fuel mixture therethrough, said means comprising a removable sleeve adapted to be inserted in the end of the outlet branch, automatically operated passage restricting means comprisinga shaft extending transversely of the sleeve and supported thereby, a suction operated flap valve pivotally mounted on said shaft and means for moving said valve toward closedposition on reduction of engine suction.

19. An intake manifold for amulticylinder internal combustion engine having a plurality of intake ports comprising, a plurality of outlet branches associated with said intake ports, automatically operated means in each branch for con trolling the flow of fuel mixture therethrough, said means comprising a removable sleeve adapted to be inserted in the end of the outlet branch, automatically operated passage restricting means comprising a shaft extending transversely of the sleeve through the axis thereof and supported thereby, a pair of suction operated flap valves pivotally mounted on the shaft and means for moving said valves toward closed position on reduction of engine suction.

20. In combination with an internal combustion engine having an intake port admitting a mixture of fuel and air to the engine combustion chamber, a conduit for supplying a mixture of fuel and air to said port, means for introducing a mixture of fuel and air into said conduit relatively'close to the intake port, and means for preventing precipitation of liquid fuel on the walls of said conduit, said means comprising fixed and variable restrictions between the point of introduction of the fuel mixture into the conduit and the engine intake valve.

21. In combination with an internal combustion engine having an intake port admitting a mixture of fuel and air tothe engine combustion chamber, a conduit for supplying a mixture of fuel and air to said port, means for introducing a mixture of fuel and air into said conduit relatively close to the intake port, and means for preventing precipitation of liquid fuel on the walls of said conduit, said means comprising a fixed restriction in said conduit adjacent the point of introduction of fuel mixture therein, and a variable restriction between the fixed restriction and the engine intake valve.

FRED E. ASELTINE. 

